The present invention generally relates to ink delivery systems, and more particularly to an ink cartridge for thermal ink jet printers and other printing systems having a substantially improved ink-retaining capacity.
Substantial developments have been made in the field of electronic printing technology. Specifically, a wide variety of highly efficient printing systems currently exist which are capable of dispensing ink in a rapid and accurate manner. Thermal inkjet systems are especially important in this regard. Printing systems using thermal inkjet technology basically involve a cartridge which includes at least one ink reservoir chamber in fluid communication with a substrate having a plurality of resistors thereon. Selective activation of the resistors causes thermal excitation of the ink and expulsion thereof from the ink cartridge. Representative thermal inkjet systems are discussed in U.S. Pat. No. 4,500,895 to Buck et al.; U.S. Pat. No. 4,794,409 to Cowger et al.; U.S. Pat. No. 4,509,062 to Low et al.; U.S. Pat. No. 4,929,969 to Morris; U.S. Pat. No. 4,771,295 to Baker et al., and the Hewlett-Packard Journal, Vol. 39, No. 4 (August 1988), all of which are incorporated herein by reference.
In order to retain suitable volumes of ink within a thermal inkjet cartridge (or any other ink cartridge), a multi-cellular absorbent member is typically used which retains ink therein. This ink may then be withdrawn on demand. For example, as stated in U..S. Pat. No. 4,771,295 to Baker et al., a conventional ether-type foam material (e.g. obtainable from the Scott Paper Company of Philadelphia, Pa. (USA)) may be used for this purpose. U.S. Pat. No. 4,794,409 to Cowger et al. discloses a thermal inkjet cartridge having a foam block therein manufactured from reticulated cellulose. Other absorbent materials used in ink Cartridge systems include but are not limited to foam rubber (U.S. Pat. No. 3,967,286 to Anderson et al.), and polyethylene and/or polyurethane foam (U.S. Pat. No. 4,306,245 to Kasugayama et al.)
However, numerous attempts have been made to increase the volumetric ink-retaining capacity of ink cartridges (e.g. thermal inkjet systems). Increased ink-retaining capacity results in improved printing efficiency, reduced printer down-time, and greater consumer economy. For example, U.S. Pat. No. 4,929,969 to Morris discloses a thermal inkjet cartridge which uses an absorbent member constructed from open cell melamine-formaldehyde condensate foam. The patent states that this material imparts improved volumetric capacity to the cartridge. U.S. Pat. No. 4,749,291 to Kobayashi et al. also discloses an ink Cartridge having an absorbent member therein manufactured from melamine-formaldehyde condensate foam.
Notwithstanding the foregoing developments, a need remains for an ink cartridge system having an improved ink-retaining capacity which uses inexpensive, readily--available materials, is easily manufactured, and enables the delivery of ink materials rapidly and effectively. The present invention Satisfies this need in a unique manner as described in detail below.